Hi .. have a Firebird (external type) numerous problems here's a list and hopefully some solutions :-
1. Burner going off after a few seconds .. flue not extended correctly.
2. No hot water flow ... lock valve on cold input collapsed.
3. Boiler not igniting .. sooted opto .. remove Rielo cover & ease out to clean.
4. Upstairs radiators warm when only using hot water .. plastic lock valve collapsed/damaged.
5. Leak through h/w flow switch .. replaced
6. Adjusting h/w temp to high makes water cold ?? I think something is reversed.